A new isomeric state in ${}^{217}\mathrm{Pa}$ has been observed with an α-decay of $E_{\alpha }=9.540\mathrm{}\pm 0.050\mathrm{MeV}$ and $T_{1/2}{=1.5\mathrm{}}_{-0.4}^{+0.9\mathrm{}}\mathrm{ms}.$ The isotope ${}^{217}\mathrm{Pa}$ was produced in the reaction ${}^{28}{\mathrm{S}\mathrm{i}+}^{194}\mathrm{Pt}$ at a beam energy of 163 MeV. Measured α-decay half-life was reproduced by the cluster model calculation with a transferred angular momentum of $l=7\mathrm{}ħ.$

• Received 23 March 1998

DOI:https://doi.org/10.1103/PhysRevC.57.R2804